Learning Resource Type

Lesson Plan

Exploring Planet Sizes and Distances

Subject Area





This lesson allows students to construct solar system models showing the comparative sizes of the planets to a scale.  The students will also use their models to carry out an investigation to analyze and interpret the distances between planets in the Solar System. This lesson uses common objects easily obtained by teachers.

This lesson was created as part of the 2016 NASA STEM Standards of Practice Project, a collaboration between the Alabama State Department of Education and NASA Marshall Space Flight Center.

    Science (2015) Grade(s): 6


    Develop and use models to determine scale properties of objects in the solar system (e.g., scale model representing sizes and distances of the sun, Earth, moon system based on a one-meter diameter sun).

    Unpacked Content



    • Model
    • Scale
    • Scale model
    • Properties
    • Size
    • Distance
    • Diameter
    • Solar system
    • Planet
    • Moon
    • Sun
    • Asteroid
    • Asteroid belt
    • Celestial body


    Students know:
    • A (scale) model is a representation or copy of an object that is larger or smaller than the actual size of the object being represented.
    • Measurements may be multiplied or divided to correctly scale objects in a model.
    • Charts and data tables may be analyzed to find patterns in data.
    • Patterns can be used to describe similarities and differences in objects in the solar system.
    • Systems and their properties may be described using more than one scale.


    Students are able to:
    • Develop a model of objects in the solar system and identify the relevant components.
    • Describe that different representations illustrate different characteristics of objects in the solar system, including differences in scale.
    • Use mathematics and computational thinking to determine scale properties.
    • Describe that two objects may be similar when viewed at one scale but may appear to be quite different when viewed at a different scale.


    Students understand that:
    • The solar system consists of the sun and a collection of objects, including planets, their moons, and asteroids that are held in orbit around the sun by its gravitational pull on them.
    • Space phenomena can be observed at various scales using models to study systems that are too large or too small.

    Scientific and Engineering Practices

    Developing and Using Models

    Crosscutting Concepts

    Scale, Proportion, and Quantity

    Primary Learning Objectives

    Students will explain the sizes and distances of the sun, Earth, moon system based on a one-meter diameter sun.

    The students will create a model of the solar system.


    Part 1: Exploring Planet Sizes

    1. Read through the Planet Sizes Student Worksheet.  This is where you will find the lesson jobs for each team.

    2. Discuss Earth, the solar system, and why we need models to help study them.

    •  Earth is the biggest thing we have ever touched, but Earth is not the biggest planet in the Solar System. We cannot just look up in the sky and see the whole Solar System and how it works. It is too big, and the planets are too far away.
    • Models let us take objects that are vastly bigger than we can understand and bring them down to a size we can understand.

    3. Show students the model Sun (the balloon blown up to 14 cm (5.5 in)). Based on the size of the model Sun, students will work in teams of four or five to answer questions 1-4 on the Planet Size Student Worksheet. These questions reveal what students currently think about planet sizes.

    4. Discuss students’ predictions and pass out the Model Planet Cards.

    5. Direct each team to choose an item from the material list and compare it to the planet on the cards. Complete the Planet Sizes Worksheet for each planet with their findings.

    6. Go around the room, having each team’s reporter give reasons why they picked each object to use for a given planet.

    7. Cut the Model Planet Cards to use in Part 2 for the walk. You may want to attach the cards to helium balloons for the walk to make the planets easy to see at a distance.


    1. Before taking the class outside, introduce the “pace” as the “ruler” for this model. A pace is two steps one with each foot. One pace is about 1 meter. You can use a meter stick for reference and for practice “pacing.”

    2. Have each team predict how far away the Earth card should be from the model Sun, using paces or meters.

    3. Take your class outside to walk the model length of the Solar System. Take the cut-up master Model Planet Cards you made in Part 1.

    4. For each planet, choose a team of students to be the official “pace setter” and “planet bearer” to fasten the planet at the correct distance.

    5. Fasten the Sun to the ground (or tie a helium balloon to a nearby object). Tell class the number of paces to Mercury, and tell students to complete the chart on their Distance Between Planets worksheet. “Walk” to Mercury, fasten the Mercury Planet Card to the ground, and repeat the process for all planets.

    NOTE: In this model, a spacecraft would move an average of 3cm (1 in) every 5 hours.

    NOTE: Be sure to point out the asteroid belt between Mars and Jupiter. Neptune was the most distant planet in the Solar System from 1979 until 1999 when Pluto passed outside of Neptune’s orbit.

    7. Back in the classroom, conclude the activity with Reflection Questions. (As a group activity or individually in science journal/notebook)

    NOTE: Be sure to remind students that the planets do not really form a straight line. They all travel around the Sun at different speeds, so they are constantly changing positions.

    Assessment Strategies

    This lesson lends itself to a variety of informal assessments.

    Check for understanding as they are completing the worksheets while conducting the investigations to explain the sizes and distances of the sun, Earth, moon system based on a one-meter diameter sun.

    Observe the students determine if they can create a model of the solar system.


    Further instructions available here will allow for the incorporation of Comets into this lessons.



    When grouping students for this lesson you may want to consider pairing students with a higher ability with those of a lesser ability to ensure greater comprehension of information being presented.

    Teacher directed role assignment can also be helpful.

    Approximate Duration

    Total Duration

    91 to 120 Minutes

    Background and Preparation


    Note: In this lesson Pluto is included. It has been recognized as a dwarf planet.

    Materials and Resources

    Materials and Resources

    Balloon (for the model sun)  

    Metric Ruler

    Miniature marshmallows

    Poppy Seeds

    Mustard Seeds

    Circle-shaped cereal

    Popcorn kernels   

    Dried peas

    Individual Gum Balls

    Black pepper


    Model Planet Cards

    Pins or masking tape



    Hard writing surface (to take outside)

    Optional: Helium balloons

    For each student:

    Planet Sizes Student Worksheet

    Distance Between Planets worksheet

    Reflection Questions

    For the Teacher:

    Worksheet Answer Key